Doesn't copyright law allow transformative works as well as satire?
Satire certainly. If by transformative you mean derivative and I think the answer to that is no, and that's exactly what the movie was - a derivative work using props and replicas of items from the original, which violates the original's copyright.
As far as I can see, it's given us a shit operating system and a bunch of shit low-brow entertainment in exchange for draconian enforcement of bunch of restrictions that no-one really seems to understand.
It's also given us OSS, because without copyrights the GPL would not be enforceable.
Without copyright, I don't think the GPL would be necessary. What would be the point of hiding the source if the executable was freely distributable? Wouldn't someone doing that just be encumbering themselves with the full development costs?
Copyrights let creators decide how their works can be used, and I'd wager much of what is produced wouldn't be absent copyrights.
I'm sure you're right with regards to massively-expensive blockbuster movies. I doubt the world would have missed them if we didn't have them though. I enjoyed Blake's 7 when I was a kid. (I don't recall ever thinking "I'd like this if not for the lack of ludicrously-expensive special effects".) That kind of low-budget entertainment would be within the means of state broadcasters.
With regards to actually useful works, copyright is good at quickly hacking together shit works, which grab mind share, and hinder the development of free works. I'd wager we would have been better off without copyright (if such a wager were possible).
As I've said, the fundamental principle is sound it's all the ways it is implemented that is broken. For example, the extension of copyright to essentially forever which prevents things from entering the public domain.
I suspect the only upside of copyright is that it's slowing the shift to the cloud, which will be even worst.